Why sometimes car vibrates at low speed?

Hi everyone. I purchased used Ford Focus 2012 a month ago and its mileage is around 40400 miles.

In the first week itself, I've noticed Screeeeeech sound while taking reverse and then applying brakes. The frequency of hearing this sound is very less.

And then after few weeks, I noticed huge vibration in steering for about 3 to 4 seconds while accelerating at lower gear.

And today, I noticed the same problem. The vibration is much greater than before and it happened when I apply brakes. The first vibration occurred when I slowed down in speed breaker and the second happened when I applie

Experienced mechanics share their insights in answering this question :
Hi There,
What you are describing is a sign of warped brake rotors. As you may know, when you press on your brake pedal, this activates a hydraulic pressure which forces small pistons inside your brake calipers to push the brake pads against the brake rotors which is what causes the stopping power you are familiar with. When this happens, an enormous amount of heat is generated due to the friction between the brake pads and rotors. As the brake rotors eventually cool down and then heat up again the next time you press on the brakes, over time this can cause them to warp slightly causing very small low spots on the surface of the brake rotor. When this happens and the brake pads are applied again to the rotors, this causes an uneven surface (on the rotor) to be applied to the flat surface brake pad, which can cause a vibration, shaking or very loud grinding sound. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your brake rotors.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Any unusual shaking or vibrating forces coming from the engine is cause for concern. It could be something as simple as old spark plugs producing an uneven power delivery, it could be something serious like worn or broken engine mounts, or it could be even more serious in the case of internal engine damage.
Some Ford Focus vehicles may exhibit an excessive engine vibration when idle. The vibration is most noticeable when the transmission is engaged in reverse. This condition may be caused by small stones, road debris, ice or snow packed/lodged in the rear engine roll restrictor.
The most prevalent cause of vibration is problems with your wheels or tires. The potential problems include improper wheel and tire balance, uneven tire wear, separated tire tread, out of round tires, damaged wheels and even loose lug nuts.
The main reason drivers will feel shaking or vibration is due to issues with the wheels or tires. Problems with the wheels or tires could include improper balance, uneven tire wear, separate tire tread, out of round tires, damaged wheels, and loose lug nuts.
It`s normal for your car to vibrate slightly when you`re driving thanks to the rotation of the crankshaft, transmission gears and other moving parts in your engine.
Some simple warning signs that the transmission is having problems: Transmission is slow to respond when shifting. Grinding, shaking, vibrating.
If the brake caliper on a wheel is faulty and causing it to stick, then it can cause car vibrations. In this particular situation, the steering wheel will be what vibrates as you reach about 40-50 miles per hour. The vibrations will get worse as you continue to accelerate at higher speeds.
A shudder or vibration may develop while driving at speeds between 35 and 40 MPH. Our technicians tell us this condition is commonly caused by a failed automatic transmission torque converter. It is recommend to replace the torque converter and install an updated powertrain control module (PCM) to correct this concern.
Motor mounts: It`s the job of the motor and transmission mounts to dampen vibration. When they break, you`ll feel excessive vibration, especially at idle. You can diagnose this yourself by putting your car in neutral. If the shaking lessens, you very well could have broken mounts.
To help confirm that the vehicle has an engine speed related vibration, with the vehicle stopped, put it into park or neutral and raise the engine speed to the RPM at which the vibration occurred to see if the vibration can be reproduced. If reproduced, diagnosis should begin with engine speed related components.
When you`re in motion at low revs your car judders, until you accelerate up to a higher speed and move into higher gears. What might be causing this? Worn engine mounts. Loose or worn engine mounts, which hold the engine to the chassis, could be the culprit.
The most common reason for a car to shake is related to tires. If the tires are out of balance then the steering wheel can shake. This shaking starts at around 50-55 miles per hour (mph). It gets worse around 60 mph but starts to get better at high speeds.
If your car shakes when accelerating, the source of the issue can range from imbalanced tires to worn-out spark plugs, loose lug nuts, and more. Most of these problems can be handled with a quick (but possibly pricey) trip to the mechanic.
THE ISSUE. Some 2000-2011 Focus vehicles may exhibit an excessive engine vibration which is most noticeable when the transmission is engaged in reverse. This condition may be caused by small stones, road debris, ice or snow that is packed or lodged in the rear engine roll restrictor.
THE ISSUE. Some 2000-2011 Focus vehicles may exhibit an excessive engine vibration which is most noticeable when the transmission is engaged in reverse. This condition may be caused by small stones, road debris, ice or snow that is packed or lodged in the rear engine roll restrictor.
CV joints are located at the end of each axle. There is both an outer and inner joint. When the inner CV joint is damaged or begins to fail, you will notice your car vibrating under hard acceleration. As it gets worse, the minor vibrations turn to violent shaking when under load.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Car not speeding up smoothly, service engine light on when first start driving and car vibrating
ANSWER : Hi There,
It sounds like you may have a dirty or faulty mass air flow sensor. The problem this can cause may also be compounded when the engine is cold due to the change in air density in cooler weather. The mass air flow sensor monitors air intake as it is mixed with fuel prior to being injected into the motor. This sensor relays information about fuel and air temperature, air speed entering the motor and many other things to the ECM which uses this to make adjustments to fuel supply to the motor. A dirty or faulty sensor can cause an imbalanced air/fuel load to be supplied to the motor which results in an over fueling or under fueling situation depending on the conditions. This type of inconsistent fuel supply to the motor may cause a hesitation, loss of power, a jerking reaction, potentially a bit of black exhaust smoke and typically a strong smell of fuel when this sensor is malfunctioning. I would suggest having a professional from Your Mechanic come to your home to diagnose and inspect your vehicle.

Car is chugging at low speeds and then stalls when I stop.
ANSWER : This may be related to a dirty or failing idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. This valve is controlled by the vehicle’s computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed. This is all controlled by the idle air control valve. When the engine RPM drops below the normal range of 750-800 RPM (for most cars), this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

Grinding/Scraping noise from the front right of the car when driving at low speeds.
ANSWER : If there were something in the way of foreign material (e.g., road debris) stuck, you’d probably hear the noise all the time. The noise may be due to the brake pads (particularly if they are not OEM pads). Non-OEM pads sometimes have chunks of metal in them and if the caliper is sticky, at take-off (i.e., while still at low speed) the pad may be rubbing against the rotor until you get to a high enough speed that the pad finally retracts. It is also possible that the brake dust cover is contacting the rotor, because it was impacted and bent, but the noise should be present all the time if that is the case. Really, the first thing to examine is the brake assembly (pads, caliper, pins in torque plate, rotor, dust cover) on the right side. If the source of the noise is not found there, obviously another rotating component is responsible and that means stuff like axles and the transmission. Be sure it is really wheel related, though. It is possible for accessory drives and pulleys to make noises, too, and such could disappear at higher RPM, just as you are describing. In any event, inasmuch as the noise is so obvious, the origin would be quickly identified during an actual, on site noise diagnostic. Such can be scheduled by YourMechanic at your convenience and performed right at your location. Please let us know if you have additional questions or concerns.

If you was hooking up a OEM cooling fan that has only 2 wires and one speed but my car has a high and low speed, what wires would you hook up?
ANSWER : Hi there. Check the high and low circuits with a digital meter for a voltage reading. The low should have a lower voltage reading than the high. I recommend putting the wires on the high selection to prevent the engine from overheating at any time. If you need further assistance with hooking up your radiator fan motor, then seek out a professional, such as one from Your Mechanic, to help you.

My car vibrates when I’m waiting at the light . It drives fine . And it vibrates more when I turn on the ac? Can itvtve motor moun
ANSWER : There are two principal possibilities: faulty motor/transaxle mounts, or an engine operating or mechanical condition including the possibility of a faulty harmonic balancer. To obtain a conclusive diagnostic, please simply request an engine vibration diagnostic and a certified Mechanic, dispatched by YourMechanic right to your location, will get this resolved. If you do need new motor/transaxle mounts, genuine OEM Nissan mounts are recommended in order to maximize the chances of resolving the problem. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Car making a low noticeable sound at speeds between 55 km/hr to 70km/hr.
ANSWER : Hi there:

Diagnosing ’noises’ remotely is one of the more difficult things to do for any mechanic. However, there are a few things which could cause this noise, ranging from loose motor mounts, loose serpentine or drive belt, pulley’s or even wheel or front end suspension issues. The best way to diagnose any problem is to have a professional mobile mechanic complete a car is making a noise inspection; so they can ride with you to attempt and replicate the noise; which will help them pinpoint the source of the noise and recommend the right repairs be completed.

Why sometimes car vibrates at low speed?
ANSWER : Hi There,
What you are describing is a sign of warped brake rotors. As you may know, when you press on your brake pedal, this activates a hydraulic pressure which forces small pistons inside your brake calipers to push the brake pads against the brake rotors which is what causes the stopping power you are familiar with. When this happens, an enormous amount of heat is generated due to the friction between the brake pads and rotors. As the brake rotors eventually cool down and then heat up again the next time you press on the brakes, over time this can cause them to warp slightly causing very small low spots on the surface of the brake rotor. When this happens and the brake pads are applied again to the rotors, this causes an uneven surface (on the rotor) to be applied to the flat surface brake pad, which can cause a vibration, shaking or very loud grinding sound. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your brake rotors.

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you